Phototube control-temperature indicating apparatus for furnices



A. WARNICK 2,457,289. PHOTOTUBE CONTROL-TEMPERATURE INDICATING Dec. 28, 1948.

APPARATUS FOR FURNACES 2 Sheets- Sheet 1 Filed Jan. 16, 1948 INVENTOR ALAN WARNICK ATTORNEY Dec. 28, 1948. A. WARNICK PHOTOTUBE CONTROL-TEMPERATURE INDICAT ING APPARATUS FOR FURNACES Filed Jan. 16, 1948 2 Sheets-Sheet 2 FIGS IN V EN TOR- ALAN WARNLcK BY ATTOR/VEY conductor, joining the phototube and rheostat, is shielded, as at 51, and this shield, as well as the phototube anode 30, is grounded as at 58.

The modification of Fig. 4 is similar to that of Fig. 3 with the exception that the phototube anode isconnected by conductor 59 to the anode of tube is at5fl i'nstead of to bridge point 34. B this means, a larger potential drop through the phototube circuit is secured.

In all forms of the invention as disclosed, it is observed that the grid of the control tube is connected to a point, as 49, 5|, 56 and 6B, lyingintermediate the phototube 3| and rheostat 36. I

Also in all forms, a capacitor 33' is connected to the control tube grid in parallel with the rheostat. Attention is directed to the fact that a ground connection of the phototube is madein.

each of the disclosed forms and that this, ground between the junctions of the respective resistors and tubes, a phototube having an anode connected to the grid of one of said tubes and to the anode of the other of said tubes and a cathode connected to the cathode of the other of said tubes, and

' means for varying the sensitivity of said photo- "tube.

connection is made to the lead-in conductor that is not directly connected to the grid of the control tube. 1

Certain important advantages result from the specific arrangements described hereinabove. The sensitivity of the apparatus is markedly improved through the use of thecoarse and fine adjustment resistors 36 and M, permitting adaptation to the requirements of any given furnace application. This sensitivity is augmented by practical elimination of stray field pickup through use of the grounded shield on conductor 32, connecting the phototube to the control grid of tube T9. In order further to develop the sensitivity of the apparatus, capacitor 33 is placed in parallel with the rheostat 36, whereby stray impulses not eliminated by the shield 31 may be filtered. By connecting the non-grid lead-in of the photo tube directly to ground as shown in the various figures, the stability of the circuit is definitely increased.

Modifications other than described may be made, the invention being comprehended in the claims hereto appended, 1 What is claimed is: s

1. An electrical circuit for temperature con trol comprising an electrical bridge circuit including two series resistors and two series vacuum tubes connected in series, one'of said tubes being provided with grid and cathode elements, a current source connected to the respective junctions of each tube and the adjacent series resistor, and a load circuit between the junctions of the respective resistors and'tubes, means in the bridge circuit for balancing the bridge at a selected temperature level, and means-for unbal ancingthe bridge at another temperature level, said means comprising a phototube connected to said grid and in parallel with the other of said tubes, whereby variation of current in said photo: tube controls the voltage of the tube grid;

2. An electrical circuit for temperature control comprising an electrical bridge circuit including two series resistorsand two series vacuum tubes connected in series, one of said tubes being-pro: vided with grid" and cathode, elements, a current source connected to'the respective junctions of each tube and the adjacent series resistor, and a load circuit between the junctions of the respec-' tive resistors and tubes, means in the bridge cir-' cuitfor balancing the bridge at a selected ternperature level, means for unbalancing the bridge at another temperature levelcomprising a phototube connected to said grid, 2. variable resistor connected between the grid and cathode of said tube for controlling the sensitivity of the phototube on the bridge balance, and a capacitor com A. An electrical circuit for temperature control comprising an electrical bridge circuit including two series resistors and two series vacuum tubes connected in series, said tubes each having an anode, cathode and grid, a current source connected to the respective junctions of each tube and the adjacent series resistor, a load circuit between the junctions of the respective resistors and tubes, a phototube having an anode connected to the grid of one of said tubes and to the anode of the other of said tubes and a cathode connected to the cathode of the other of said tubes, means for varying the sensitivity of said phototube, and means for shielding the grid connection of said phototube from stray voltage impulses.

5. An electrical circuit for temperature control comprising an electrical bridge circuit includ;ng two series resistors and two series vacuum tubes connected in series, each of said tubes being provided with an anode, cathode and grid, 2. current source connected to the respective junctions of each tube and the adjacent series resistor, a load circuit between the junctions of the respective resistors and tubes, means in the bridge circuit for balancing the bridge at a selected temperature level, a phototube having anode and cathode elements, a conductor intermediate one of said phototube elements and the grid of one of said tubes, and a grounded shield enclosing said conductor, the other of said phototube elements being connected to said grounded shield.

6. An electrical circuit for temperature control comprising an electrical 4-branch bridge circuit including two series resistors and two series vacuum tubes connected in series, one of said tubes being provided with grid and cathode ele-- ments, a current source connected to the respective junctions of each tube and the adjacent series resistor, and a load circuit between the junctions of the respective resistors and tubes, means in one branch of the bridge circuit for balancing the bridge at a selected temperature level, means for unbalancing the bridge at another temperature levelincluding a phototube connected to said grid, a variable resistor connected between the grid and cathode of said one tube, and a variable resistor in said bridge load circuit, whereby the sensitivity of the phototube on the bridge balance may be controlled.

'7. An electrical circuit for temperature control comprising an electrical bridge circuit including two series resistors and two series vacuum tubes connected in series, one of said tubes being provided with grid and cathode elements, a current source connected to the respective junctions of each tube and the adjacent series resistor, and a load circuit between the junctions of the respective resistors and tubes, means in the bridge circuit for balancing the bridge at a selected temperature level, means for unbalancing the bridge at another temperature level including a phototube connected to said grid, sensitivity means including a variable resistor connected between the grid and cathode of said one tube, and a variable resistor in said bridge load circuit, whereby the sensitivity of the phototube on the bridge balance may be controlled, and means for securing an initial balance of said bridge.

8. An electrical circuit for temperature control comprising an electrical bridge circuit including two series resistors and two series vacuum tubes connected in series, one of said tubes being provided with grid and cathode elements, a, current source connected to the respective junctions of each tube and the adjacent series resistor, and a load circuit between the junctions of the respective resistors and tubes, means in the bridge circuit for balancing the bridge at a selected temperature level, andmeans for unbalancing the bridge at another temperature level, said unbalancing means comprising the phototube, circuit connections forming therewith a parallel circuit around the other of said tubes, and a conductor connection between said tube grid and an intermediate point on said parallel circuit.

9. An electrical circuit for temperature control comprising an electrical bridge circuit including two series resistors and two series vacuum tubes connected in series, one of said tubes being provided with grid and cathode elements, a current source connected to the respective junctions of each tube and the adjacent series resistor, and a load circuit between the junctions of the respective resistors and tubes, means in the bridge circuit for balancing the bridge at a selected temperature level, and means for unbalancing the bridge at another temperature level, said unbalancing means comprising the phototube, circuit connections forming therewith a parallel circuit around the other of said tubes, and a conductor connection between said tube grid and an intermediate point on said parallel circuit, the phototube connection other than that connected to said grid being grounded.

10. An electrical circuit for temperature control comprising a source of direct current, a bridge network connected across said source for supply of power therefrom, means for balancing said bridge at a given temperature level, and means for unbalancing said bridge at another temperature level, said bridge comprising four resistors connected across said source in two parallel paths, each including two of said resistors in series, bridge-output points between the junctions of each pair of resistors, and power mechanism connected to bridge output points, and. said unbal-' an-cing means comprising a phototube, circuit means for connecting the phototube in parallel with one of said bridge resistors, and means electrically connected between said phototube circuit and another of said bridge resistors for varying the resistance of said other resistor in accordance with the current flow in said phototube circuit.

11. An electrical circuit for temperature control comprising a source of direct current, a bridge network connected across said source for supply of power therefrom, means for balancing said bridge at a given temperature level, means for unbalancing said bridge at another temperature level, and sensitive means for varying the sensitivity of said unbalancing means, said bridge comprising four resistors connected across said source in two parallel paths, each including two of said resistors in series, bridge-output points between the junctions of each pair of resistors, and power mechanism connected to bridge output points, said unbalancing means comprising a phototube, circuit means for connecting the phototube in parallel with one of said bridge resistors, and means electrically connected between said phototube circuit and another of said bridge resistors for varying the resistance of said other resistor in accordance with the current flow in said phototube circuit, and said sensitivity means comprising a variable resistor connected in series with said phototube.

12. An electrical circuit for temperature control comprising a source of direct current, a bridge network connected across said source for supply of power therefrom, means for balancing said bridge at a, given temperature level, means for unbalancing said bridge at another temperature level, and sensitive means for varying the sensitivity of said unbalancing means, said bridge comprising four resistors connected across said source in two parallel paths, each including two of said resistors in series, bridge-output points between the junctions of each pair of resistors, and power mechanism connected to bridge output points, said unbalancing means comprising a phototube, circuit means for connecting the phototube in parallel with one of said bridge resistors, and means electrically connected between said phototube circuit and another of said bridge resistors for varying the resistance of said other resistor in accordance with the current flow in said phototube circuit, and said sensitivity means comprising a variable resistor connected in series with said phototube, and a second variable resistor connected between said bridge output points in series with said power mechanism.

ALAN WARNICK.

No references cited. 

